1. Field of the Invention
The present invention relates to structures of interconnections for electrically interconnecting elements and terminals of circuits in semiconductor devices and a method for the fabrication of such interconnection structures.
2. Description of the Related Art
Aluminum (Al) films have been widely used as interconnection films in semiconductor devices because their resistance is low, they can easily make ohmic contacts with silicon (Si), and they can make very intimate contact with insulating films such as SiO.sub.2 films or the like. Aluminum films can also reliably prevent the occurrence of electromigration and stressmigration resulting from the increasing reduction in the width of interconnection films; the advantages of using copper (Cu) films as interconnection films have been reported in conferences and the like (for instance, Y. Arita et. al. "CVD COPPER METAL-LURGY FOR ULSI INTERCONNECTIONS". IEEE-IEDMECH. DIG.:pp 39-42).
Meanwhile, in the case of patterning interconnection film patterns and especially when defining an extreme interconnection film pattern, chlorine compound gases such as Cl.sub.2 which can minimize undercuts, have been widely used in the dry etching process.
However, in the case of the dry etching process of Al and Cu films with HCl gas, chlorides such as AlCl.sub.3, CuCl.sub.2 and the like frequently tend to remain after dry etching. It follows therefore that these remaining chlorides react with water, producing hydrogen chloride. As a result, there arises a problem that the interconnection films are corroded within a short time. Thus, it has been impossible to fabricate highly reliable interconnection films by the above-described prior art methods.
The present invention, therefore, was made to overcome the problems encountered in the fabrication of interconnection films by the prior art fabrication methods and strives to provide highly reliable and dependable interconnection structures for semiconductor devices and a method for fabrication thereof.